Question

在C#中如何将字符串写入文本文件

Answer 1

1、首先我们以一串字符串为例，首先定义一个字符串string s = "abcdefgh";

2、之后的格式是System.IO.File.WriteAllText，或者是.WriteAllLine、.WriteAllBytes等。对于字符串可以System.IO.File.WriteAllText比较好，对于字符串数组用System.IO.File.WriteAllLine比教好

3、我们以System.IO.File.WriteAllText为例，我们会发现它有两个重载，两个重载都会有两个内容一个是写入文件路径和文件名，另外一个是字符串的名字。不同在于最后的编码Encoding.Default上

4、之后我们输入我们的文件位置，及其文件名。其中路径文件名要在“”下，文件名的后缀千万不要忘记写，我们就以txt为例

5、之后键入的是我们的字符串的变量名，最后最好加上Encoding.Default，来防止编码问题

6、我们按F5执行下，我们就可以到C盘打开我们的文件，我们会看到，我们的字符串已经成功写入到文件中

Answer 2

string logPath = HttpContext.Current.Server.MapPath("log.txt");
//指定一个相当路径
System.IO.StreamWriter sw = new System.IO.StreamWriter(logPath, true, Encoding.UTF8);
sw.WriteLine("你要写入的内容");
sw.Close();

Answer 3

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace WindowsFormsApplication1
{
/// <summary>
/// WriteInLog 的摘要说明。
/// </summary>
public class WriteInLog
{
private string logFileName;
private int logFileSizes;

/// <summary>
/// 写入日志文件
/// </summary>
public WriteInLog()
{
logFileName = @"d:\logfile.txt";
}

/// <summary>
/// 自动删除日志文件大小,此方法已经重载.
/// </summary>
/// <param name="fileSize">日志文件大小,单位KB</param>
public WriteInLog(int fileSize)
: this()
{
if (fileSize != 0)
{
this.logFileSizes = fileSize * 1024;
}
else
{
this.logFileSizes = 1024;
}
}
/// <summary>
/// 日志文件完全名,如:@"e:\logfile.txt"
/// </summary>
public string LogFileName
{
set
{
this.logFileName = value;
}
}

/// <summary>
/// 写入日志信息
/// </summary>
/// <param name="msg">日志内容</param>
/// <param name="IsAutoDelete">是否自动删除日志</param>
public void writeInLog(string msg)
{
if (logFileSizes != 0)
{
writeInLog(msg, true);
}
else
{
writeInLog(msg, false);
}
}

/// <summary>
/// 写入日志信息
/// </summary>
/// <param name="msg">日志内容</param>
/// <param name="IsAutoDelete">是否自动删除日志</param>
private void writeInLog(string msg, bool IsAutoDelete)
{
try
{
FileInfo fileinfo = new FileInfo(logFileName);
if (IsAutoDelete)
{
if (fileinfo.Exists && fileinfo.Length >= logFileSizes)
{
fileinfo.Delete();
}
}
using (FileStream fs = fileinfo.OpenWrite())
{
StreamWriter sw = new StreamWriter(fs);
sw.BaseStream.Seek(0, SeekOrigin.End);
sw.WriteLine("=====================================");
sw.Write("添加日期为:" + DateTime.Now.ToString() + "\r\n");
sw.Write("日志内容为:" + msg + "\r\n");
sw.WriteLine("=====================================");
sw.Flush();
sw.Close();
}
}
catch (Exception ex)
{
ex.ToString();
}
}

}

}

你只要调用这个方法，把字符串输入就行的，文本保存的地址你可以自个改
/// <summary>
/// 写入日志信息
/// </summary>
/// <param name="msg">日志内容</param>
/// <param name="IsAutoDelete">是否自动删除日志</param>
public void writeInLog(string msg)
{
if (logFileSizes != 0)
{
writeInLog(msg, true);
}
else
{
writeInLog(msg, false);
}
}

Answer 4

string fullPath ="C:/a.txt";
if (System.IO.File.Exists(fullPath))
{
using (StreamWriter sw = new StreamWriter(fullPath,false,Encoding.Default))
{
sw.WriteLine("aaa");
}
}